Tunable Cathodoluminescence Properties of Tb[sup 3+]-Doped La[sub 2]O[sub 3] Nanocrystalline Phosphors

Abstract

Nanocrystalline Tb 3+ -doped La 2 O 3 phosphors were prepared through a Pechini-type sol-gel process. X-ray diffraction ͑XRD͒, field-emission-scanning electron microscopy ͑FESEM͒, photoluminescence, cathodoluminescence ͑CL͒ spectra, and lifetimes were utilized to characterize the synthesized phosphors. The XRD results revealed that a pure La 2 O 3 phase can be obtained at 700°C. FESEM images indicated that the La 2 O 3 :Tb 3+ phosphors are composed of aggregated spherical particles with sizes ranging from 60 to 100 nm. Under the excitation of UV light and low voltage electron beams ͑0. Although LCDs hold almost more than 50% of the market for flat panel displays, in demanding applications found in military applications, medical instruments, vehicles, and dusty environments, the weaknesses of LCDs are severe, viz., small viewing angle, limited operation temperature, relatively low brightness, and sensitivity for constant movement.2-4 Therefore, a considerable amount of research has been focused on the development of emissive flat panels. Among the emissive display technologies, field-emission displays ͑FEDs͒ have been developed as one of the most promising flat panel displays due to its potential to provide displays with thin panel thickness, self-emission, wide viewing, quick response, high brightness, high contrast ratio, light weight, and low power consumption. 5,6 Monocolor Spindt-type FEDs have been supplied to the market, and they have proven good reliability and performance since 7 years ago, 7 and preparation for mass production of color FEDs had started in recent years. Fundamentally, FEDs are constructed by three elemental parts, such as micro or nanofabrication of emitters, vacuum packaging, and phosphor anodes. Each of the three elements is essential to realize FEDs with interrelationship. 7,8 FEDs must operate at significantly lower excitation voltages ͑Յ5 kV͒ and higher current densities ͑10-100 A/cm 2 ͒ than CRTs. Thus phosphors for FEDs are required to have a high efficiency at low voltages, high resistance to current saturation, long service time, and equal or better chromaticity than CRT phosphors. 9The demand for high resolution and increased efficiency in phosphors for FEDs has promoted the development of phosphors that perform at low voltages.10-14 Many efficient sulfide-based phosphors, such as Y 2 O 2 S:Eu, Gd 2 O 2 S:Tb, SrGa 2 S 4 :Eu, Zn͑Cd͒S:Cu,Al, ZnS:Ag,Cl, etc., have been explored as possible low voltage phosphors.15-18 Unfortunately, sulfide phosphors are easy to decompose and to emit sulfide gases under the electron excitation, subsequently causing the cathodes to deteriorate, thus lowering the lifetime and luminous efficiency of phosphors. 19,20 Oxide-based phosphors are more stable and environmental friendly in comparison with sulfides. Therefore, rare-earth-doped oxide-based phosphors for FEDs have been of great interest due to their excellent light output, color rendering properties, and superior stability under electron bombardment. [21][22][23] One of the promising candidate...

Lanthanum cerate (La2Ce2O7): hydrothermal synthesis, characterization and optical properties

“…The five intensive peaks that are corresponded to the pure La 2 Ce 2 O 7 phase are in agreement with the literature [12,[17][18][19]. As shown in Table 2, there are five peaks similar to those of [27][28][29]. Comparison of the data in Tables 1 and 2 show that by changing the conditions from deionized water to basic solution the crystals' growth has increased but the material was not obtained as a pure phase.…”

Proton, UV, and X-ray Induced Luminescence in Tb3+ Doped LuGd2Ga2Al3O12 Phosphors

“…These values indicate that with the increase of Tb concentration from 0.1 mol% to 5 mol% of Tb 3+ the bluish emission changes to greenish. This result matches well with the published materials [29].…”

Thulium Oxide Nanopowders Obtained by Precipitation

“…The interest in the applications of rare‐earth‐based materials covers many different fields, including energy, photonics and electronics. Among the most studied rare‐earth oxide materials are Gd 2 O 3 , Y 2 O 3 , and La 2 O 3 . However, Tm 2 O 3 has been less frequently studied.…”